Allow navigations to frames that aren't being unloaded in the unload handler.

third_party/WebKit/Source/core/loader/NavigationScheduler.cpp

Index: third_party/WebKit/Source/core/loader/NavigationScheduler.cpp
diff --git a/third_party/WebKit/Source/core/loader/NavigationScheduler.cpp b/third_party/WebKit/Source/core/loader/NavigationScheduler.cpp
index a52bf28c0827f5310a0e239a0d70378389b47b14..95080bcbd1c51f678c4b45b101ec881f8e09e90d 100644
--- a/third_party/WebKit/Source/core/loader/NavigationScheduler.cpp
+++ b/third_party/WebKit/Source/core/loader/NavigationScheduler.cpp
@@ -106,8 +106,6 @@ void maybeLogScheduledNavigationClobber(ScheduledNavigationType type,
 
 }  // namespace
 
-unsigned NavigationDisablerForUnload::s_navigationDisableCount = 0;
-
 class ScheduledNavigation
     : public GarbageCollectedFinalized<ScheduledNavigation> {
   WTF_MAKE_NONCOPYABLE(ScheduledNavigation);
@@ -365,36 +363,13 @@ bool NavigationScheduler::isNavigationScheduledWithin(double interval) const {
   return m_redirect && m_redirect->delay() <= interval;
 }
 
-// TODO(dcheng): There are really two different load blocking concepts at work
-// here and they have been incorrectly tangled together.
-//
-// 1. NavigationDisablerForUnload is for blocking navigation scheduling during
-//    a beforeunload or unload events. Scheduled navigations during
-//    beforeunload would make it possible to get trapped in an endless loop of
-//    beforeunload dialogs. Scheduled navigations during the unload handler
-//    makes is possible to cancel a navigation that was initiated right before
-//    it commits.
-//
-//    Checking Frame::isNavigationAllowed() doesn't make sense in this context:
-//    NavigationScheduler is always cleared when a new load commits, so it's
-//    impossible for a scheduled navigation to clobber a navigation that just
-//    committed.
-//
-// 2. FrameNavigationDisabler / LocalFrame::isNavigationAllowed() are intended
-//    to prevent Documents from being reattached during destruction, since it
-//    can cause bugs with security origin confusion. This is primarily intended
-//    to block /synchronous/ navigations during things lke
-//    Document::detachLayoutTree().
 inline bool NavigationScheduler::shouldScheduleReload() const {
-  return m_frame->page() && m_frame->isNavigationAllowed() &&
-         NavigationDisablerForUnload::isNavigationAllowed();
+  return m_frame->page() && m_frame->isNavigationAllowed();
 }
 
 inline bool NavigationScheduler::shouldScheduleNavigation(
     const String& url) const {
-  return m_frame->page() && m_frame->isNavigationAllowed() &&
-         (protocolIsJavaScript(url) ||
-          NavigationDisablerForUnload::isNavigationAllowed());
+  return m_frame->page() && m_frame->isNavigationAllowed();
 }
 
 void NavigationScheduler::scheduleRedirect(double delay, const String& url) {